I. Field of the Invention
This invention relates generally to temperature telemetering apparatus, and more particularly to an electronics module adapted for placement in an opening drilled into the surface of a pavement for sensing pavement surface temperature and telemetering temperature readings to a remote receiver whereby a determination can be made whether to apply anti-icing chemicals to the roadway.
II. Discussion of the Prior Art
In U.S. Pat. No. 6,695,469 to Leonhardt and assigned to Energy Absorption Systems, Inc., there is described a roadway freezing-point monitoring system including a module adapted to be inserted into a opening drilled in the roadway pavement surface such that the top surface of the module is flush with the roadway surface. Contained within the module is a thermal-couple temperature sensor, a random access memory, a read-only memory and a memory controller. The memories and memory controller receive power over a pair of wires in the cable 18. Cable 18 also includes a conductor over which digital data may be sent to an external roadside base station. Several such modules may be coupled via hard wire connections to the base station which, in turn, is coupled via a network to a remote computer.
The system described in the Leonhardt '469 patent is operative to provide information to personnel at a remote site of the need, if any, for applying freezing point reducing chemicals to the roadway surface at particular locations to avoid formation of ice on the roadway surface.
The modules described in the prior art Leonhardt '469 patent suffer from the fact that a trench must be dug through the concrete or asphalt road surface to accommodate the cable over which electrical power is brought to the module from a roadside source and over which digital data from the module to the roadside base station is transmitted. The trench must later be filled with patching cement or asphalt and this greatly increases the installation cost. Moreover, if plural modules are disposed in the roadway to monitor temperature in multiple lanes, it can adversely affect the integrity of the road surface leading to break up due to ingress of moisture and subsequent freezing and thawing action.
Another feature that is advantageous in a roadway temperature sensing module is the ability to determine whether the surface of the roadway is being heated from above, i.e., from the sun, or is being heated from below, i.e., via the road bed.
This knowledge assists in the determination of what type of anti-icing/de-icing treatment to employ and provides guidance on the timing and location of the treatment. For example, if the sun is shining, the road surface is being warmed from the sun, and the forecast is for a nighttime air temperature just below freezing; a suitable treatment would be to treat the roadway before sundown, knowing that the sun and anti-icing/de-icing agent will work together to melt the ice or remove the ice from the road surface. However, if the sun is shining, the road surface is being warmed from the ground, and the forecast is for a nighttime air temperature just below freezing; it may be best to not treat the road at all or to delay treatment until early morning, knowing that the ground will assist in keeping the roadway surface free from ice.
It is accordingly a principal object of the present invention to provide an improved roadway temperature sensing module.
Another object of the invention is to provide a self-contained roadway temperature sensing module that does not require operating power from a roadside location proximate the module.
Yet another object of the invention is to provide a roadway temperature sensing module capable of telemetering temperature data from one or more sensing elements in the module to a remote receiver station via wireless transmission.
Still another object of the present invention is to provide a module adapted to be embedded in a roadway and that provides multiple temperature sensing elements therein whereby the direction of heating of the roadway surface can be determined.